[Bug 57805] New: Wine CoreMIDI: Extra program change event on sending program change through MIDI Output from winmm

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57805

Bug ID: 57805
           Summary: Wine CoreMIDI: Extra program change event on sending
                    program change through MIDI Output from winmm
           Product: Wine
           Version: unspecified
          Hardware: aarch64
                OS: MacOS
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: winecoreaudio.drv
          Assignee: [e-mail]
          Reporter: [e-mail]

Created attachment 78012
  --> https://bugs.winehq.org/attachment.cgi?id=78012
Screen shot of the sample output

I tried to use Falcosoft SoundFont Player 6 (a MIDI player) using Wine on
MacOS, I tried to play some MIDI files through it but it always seem to be
stuck on program 00 (Acoustic Grand Piano) on all tracks.

I tried to capture the MIDI output data through Pocket MIDI (a free MacOS app
something like MIDI-OX on Windows), it seems there is an error on sending 2
byte messages such as Program Change. Attached is the sample output from
sending one program change from the UI.

Expected output the Program Change message should only be sent once, not twice.

[Bug 57805] Wine CoreMIDI: Extra program change event on sending program change through MIDI Output from winmm

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57805

Brendan Shanks  changed:

What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[e-mail]

--- Comment #1 from Brendan Shanks  ---
I was able to test this by enabling the IAC driver in Audio MIDI Setup, then
having Pocket MIDI in Wine send data to native Mac Pocket MIDI.
The bug shows up with Program Change or Channel Aftertouch messages (both 2
bytes). The Windows MODM_DATA message always includes 3 bytes, and the docs say
that "the driver must parse the event to determine how many bytes to transfer".
We do not do that, and are just passing all 3 bytes to Core MIDI. Core MIDI
must be doing some parsing, as 1 byte messages are sent without an issue. But
for these 2 byte messages, we need to only send those 2 bytes to Core MIDI.

An MR with a fix is up at:

https://gitlab.winehq.org/wine/wine/-/merge_requests/7348

[Bug 57805] Wine CoreMIDI: Extra program change event on sending program change through MIDI Output from winmm

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=57805

--- Comment #2 from Brendan Shanks  ---
This should be fixed by
https://gitlab.winehq.org/wine/wine/-/commit/d95513b424ea0ebb192d424f773ba74...